METHOD AND APPARATUS FOR OPTIMIZING FRESH WATER GENERATION SYSTEM OF MARINE VESSEL COMPRISING HYBRID DESALINATION PLANT

TECHNICAL FIELD

[0001] The present application generally relates to optimizing fresh water generation by a hybrid desalination plant at a marine vessel.

BACKGROUND

[0002] This section illustrates useful background information without admission of any technique described herein representative of the state of the art.

[0003] Different solutions exist for fresh water generation. Possible fresh water sources for marine vessels include, for example, fresh water generation from sea water and bunkering in a port.

[0004] During a typical marine voyage there are multiple methods to produce water. Namely multistage flash (MSF) system where the water is flashed in multiple stages and condensated through a series of pipe where the sea water is passed through them. In addition, reverse osmosis (RO) membrane system is used quite widely in the marine sector. Both systems have their pros and cons, where MSF can be more reliable but more expensive to run, while RO is much cheaper to run and perfect for drinking water.

[0005] Seawater around the marine vessel may be pumped and used, depending on the operation setup.

[0006] In today’s marine vessels, controlling energy management systems, power management systems, smart water generation systems, as well as navigation systems together requires still a more manual approach of the systems.

[0007] However, when planning an optimal configuration for a marine vessel, there are vast number of parameters and factors that affect the overall efficiency of the marine vessel due to complexity of the fresh water generation, energy production, energy consumption, environmental conditions and restrictions as well as navigational matters. When considering smart fresh water generation as part of the equation using hybrid desalination plant, that makes optimal efficiency control challenging.

[0008] Thus, a solution is needed to enable accurate, efficient, and reliable method for optimization of a hybrid desalination plant for a marine vessel.

SUMMARY

[0009] Various aspects of examples of the invention are set out in the claims.

[0010] According to a first example aspect of the present invention, there is provided a computer-implemented method for optimizing fresh water generation system of a marine vessel, wherein the fresh water generation system comprises a hybrid desalination plant comprising a multi stage flash (MSF) subsystem and a reverse osmosis (RO) subsystem, and the method comprising: determining a reverse osmosis (RO) model using membrane recovery ratio (RR) and distillate flow rate; determining a multi stage flash (MSF) model using brine salinity, feed salinity and fresh water mass flow rate; receiving target fresh water flow rate, target fresh water salinity and seawater temperature information; and determining hybrid desalination plant configuration using the reverse osmosis (RO) model, the multi stage flash (MSF) model and the target fresh water flow rate, the target fresh water salinity and the seawater temperature information.

[0011] In an embodiment, the fresh water generation system is controlled using the hybrid desalination plant configuration.

[0012] In an embodiment, the multi stage flash (MSF) model is configured to use at least one of the following parameters: number of pipes in a condenser, diameter of condenser pipes; heat transfer area in stages, heat exchanger output temperature, and condenser pipe length.

[0013] In an embodiment, the multi stage flash (MSF) subsystem is a water desalination process where seawater is distilled by flashing portions of the seawater through multiple stages and each stage contains a condenser and areas where fresh water is collected. [0014] In an embodiment, the stages are connected to each other and a pressure of a first stage is reduced by utilising an ejector pump to decrease ambient pressure and to decrease boiling point of the seawater for allowing flashing to occur.

[0015] In an embodiment, the multi stage flash (MSF) model is defined using a transient fluid dynamics model.

[0016] In an embodiment, the hybrid desalination plant comprises common seawater intake systems for the multi stage flash (MSF) subsystem and the reverse osmosis (RO) subsystem.

[0017] In an embodiment, the method further comprises: controlling distillate production from the multi stage flash (MSF) subsystem to be blended with the reverse osmosis (RO) subsystem permeate in order to obtain desired water quality.

[0018] In an embodiment, the hybrid desalination plant is configured to use at least one stage of the multi stage flash (MSF) subsystem and a reverse osmosis (RO) subsystem.

[0019] In an embodiment, the method further comprises: determining hybrid desalination plant configuration by increasing relative use of the reverse osmosis (RO) subsystem when the seawater temperature increases.

[0020] In an embodiment, the method further comprises: receiving desired water information; and controlling the hybrid desalination plant to blend water production of the multi stage flash (MSF) subsystem and the reverse osmosis (RO) subsystem based on the desired water information.

[0021] In an embodiment, the reverse osmosis (RO) subsystem is configured to utilize electrical power and the multi stage flash (MSF) subsystem is configured to utilize heat and electrical power.

[0022] In an embodiment, the method further comprises controlling the reverse osmosis (RO) subsystem to be operated at a reduced load.

[0023] In an embodiment, the method further comprises: determining first cost information for the reverse osmosis (RO) subsystem based on the reverse osmosis (RO) model; determining second cost information for the multi stage flash (MSF) subsystem based on the multi stage flash (MSF) subsystem model; and determining hybrid desalination plant configuration using the first and second cost information.

[0024] In an embodiment, the first and second cost information comprise capital cost information and operational cost information.

[0025] In an embodiment, the first and second cost information is determined by following equation: wherein CDM relates to direct capital cost, CIM relates to indirect capital investment and COM relates to operating costs.

[0026] In an embodiment, the method further comprises determining hybrid desalination plant to comprise the reverse osmosis (RO) subsystem and the multi stage flash (MSF) subsystem to operate independently but sharing a common inlet.

[0027] In an embodiment, the method further comprises controlling throughput to be shared between the reverse osmosis (RO) subsystem and the multi stage flash (MSF) subsystem so that 25-40% of the fresh water is produced by the multi stage flash (MSF) subsystem and 60-75% of the fresh water is produced by the reverse osmosis (RO) subsystem.

[0028] In an embodiment, 30-35% of the fresh water is produced by the multi stage flash (MSF) subsystem and 65-70% of the fresh water is produced by the reverse osmosis (RO) subsystem.

[0029] In an embodiment, the method further comprises: determining hybrid desalination plant configuration using seawater characteristic information that comprises at least one of the following: seawater temperature information; seawater salinity information; and seawater quality information.

[0030] According to a second example aspect of the present invention, there is provided a marine vessel control apparatus for optimizing fresh water generation system of a marine vessel, wherein the fresh water generation system comprises a hybrid desalination plant comprising a multi stage flash (MSF) subsystem and a reverse osmosis (RO) subsystem, the apparatus comprising: a communication interface for transceiving data; at least one processor; and at least one memory including computer program code; the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus to: determine a reverse osmosis (RO) model using membrane recovery ratio (RR) and distillate flow rate; determine a multi stage flash (MSF) model using brine salinity, feed salinity and fresh water mass flow rate; receive target fresh water flow rate, target fresh water salinity and seawater temperature information; and determine hybrid desalination plant configuration using the reverse osmosis (RO) model, the multi stage flash (MSF) model and the target fresh water flow rate, the target fresh water salinity and the seawater temperature information.

[0031] According to a third example aspect of the present invention, there is provided a computer program embodied on a computer readable medium comprising computer executable program code, which code, when executed by at least one processor of an apparatus, causes the apparatus to: determine a reverse osmosis (RO) model using membrane recovery ratio (RR) and distillate flow rate; determine a multi stage flash (MSF) model using brine salinity, feed salinity and fresh water mass flow rate; receive target fresh water flow rate, target fresh water salinity and seawater temperature information; and determine hybrid desalination plant configuration using the reverse osmosis (RO) model, the multi stage flash (MSF) model and the target fresh water flow rate, the target fresh water salinity and the seawater temperature information. [0032] Different non-binding example aspects and embodiments of the present invention have been illustrated in the foregoing. The embodiments in the foregoing are used merely to explain selected aspects or steps that may be utilized in implementations of the present invention. Some embodiments may be presented only with reference to certain example aspects of the invention. It should be appreciated that corresponding embodiments may apply to other example aspects as well.

BRIEF DESCRIPTION OF THE DRAWINGS

[0033] For a more complete understanding of example embodiments of the present invention, reference is now made to the following descriptions taken in connection with the accompanying drawings in which:

[0034] Fig. 1 shows a schematic picture of a marine vessel and a system according to an example embodiment of the invention;

[0035] Fig. 2 presents an example block diagram of a control apparatus in which various embodiments of the invention may be applied;

[0036] Fig. 3 shows a schematic picture of a hybrid desalination plant (HDP) configuration and related information flows according to an example embodiment;

[0037] Fig. 4 presents an example block diagram of a server apparatus in which various embodiments of the invention may be applied;

[0038] Fig. 5 shows a flow diagram showing operations in accordance with an example embodiment of the invention;

[0039] Fig. 6 shows a fresh water generation system in accordance with an example embodiment of the invention; and

[0040] Fig. 7 shows a fresh water generation system in accordance with an example embodiment of the invention.

DETAILED DESCRIPTION OF THE DRAWINGS

[0041] In the following description, like numbers denote like elements.

[0042] Embodiments of the invention relate to automated route plan or operation management system of a marine vessel for a voyage between ports or waypoints, for example. [0043] Power production and propulsion system have been targets for continuous adjustment, control and monitoring to achieve optimal efficiency with respect to the vessel performance. Power control and operation optimization is a fundamental part of the control system of a vessel. Likewise, the propulsion system is controlled to produce the required power by using the available electric and/or primary energy. In practice, however, the sufficiency of energy has not been as critical as the efficiency of the devices and their control systems.

[0044] By controlling the power, optimization route, driving profile and operations of the separate devices on board, energy can be consumed efficiently and economically. This applies e.g. for gas system operations, such as reliquefaction, individual propulsion units, pumps, automation, fresh water generation system, lighting and heating equipment, as well as other auxiliary devices.

[0045] Many other factors affect the overall energy efficiency of the marine vessel and should be considered in the ship performance including optimization and configuration of the power plant of the ship, choice of fuel type, the trim and list of the ship and the planned route.

[0046] A computer software implemented simulation, or a computer software implemented model, is a computer program that is configured to simulate an abstract model of a system. Optimization of ship energy performance, like energy consumption, has been performed by creating such computer-implemented simulation models that describe relationships and dependencies between operational variable factors of the ship and parameters presenting input variables that these factors depend on. The models enable prediction of the behavior of the system from a set of parameters and initial conditions.

[0047] The reliability and the trust that can be put in such computer simulations depend on the validity of the simulation model.

[0048] Modeling the dependencies between the performance variable and the affecting input variables are complicated and based on empirical methods. Trustworthy model requires deep understanding on both energy production and consumption. Prior art methods require human effort and manual setting of parameters as well as manual system control based on the model output. [0049] The object of this invention is to develop simulation models that give more detailed and reliable information about different factors affecting the ship energy performance and control vessel automation in accurate and efficient way.

[0050] In an embodiment, automation, power management and energy management systems are configured to be operated together so that a support tool and scheduler is developed that can either assist the chief engineer in optimizing the use of the on-board systems and schedule the activities for each system or control the board system automatically to support better autonomous marine vessels, for example.

[0051] Different operating schedules may be defined, such as basic operation mode, electronic operation mode and automated operation mode, for example. Within the basic operation mode, schedule information can be provided in printed form or electronically to the engine crew and use for scheduling the use of equipment based on energy consumption and generation. Within the electronic operation mode, the schedule information can be provided as embedded into the main systems providing the schedule in electronic format along with a notification prior to every new task to be performed and a request for acknowledge. Within the automated operation mode, the schedule information can be provided embedded into the main systems scheduling and further executing the use of equipment and energy generation with a mere notification to the engine crew or remote-control station.

[0052] Currently it is still common that fresh water generation systems, energy management systems and power management systems are operated separate from navigation systems, which requires a manual approach to the operation and management of the systems. Disclosed embodiments are configured to automate the interaction between the navigational route planning and the energy route planning. Such operation may include scheduling of energy consumption (use of equipment) and energy generation along with when to use different types of fuel/propulsion/exhaust gas cleaning system (e.g. SOx or NOx cleaning systems) to comply with local environmental requirements, for example. [0053] By allowing an extended exchange of data between more systems, it makes it possible to create a better optimization and utilization of the on-board systems and it makes the work of the chief engineer easier to plan and perform.

[0054] Typically, fresh water sources for ships comprise fresh water generation from sea water and bunkering in a port. Various types of fresh water generators used on board ships are mainly reverse osmosis (RO) plant and evaporators.

[0055] Working principle of reverse osmosis plants can shortly be summarized as follows. Reverse osmosis (RO) is a water treatment process that removes contaminants from sea water by using pressure to force water molecules through a semipermeable membrane. During this process, the contaminants are filtered out and flushed away, leaving clean water.

[0056] Working principle evaporators can shortly be summarized as follows. Process utilizes separating fresh water from sea water by boiling sea water in evaporators and evaporated vapor is condensated in the condenser.

[0057] There can be different configurations used for fresh water production on board, such as: Only evaporators, only reverse osmosis, and both technologies installed.

[0058] Both technologies RO and EV have advantages and disadvantages.

[0059] Costs of fresh water productions depend on availability of heat, electricity, sea water quality and water price in ports. To achieve cost and energy savings different methods can be used depending on conditions. Also, water consumption onboard is changing because of ambient air temperature, location of the ship, usage of equipment that is consuming a lot of water, like washing machines. Filling swimming pools requires high amount of water too.

[0060] There are some criteria, which should be taken into attention during selection of fresh water source. Performance of reverse osmosis plants is sensitive for sea water temperature (lower temperature means lower capacity), sea water salinity and turbidity. In some areas reverse osmosis plants cannot be used because of poor quality of sea water. Using of fresh water generators in ports should be avoided. [0061] In an embodiment, a hybrid fresh water generation system is provided where the operation is controlled by a dynamic hybrid model (DHM). The hybrid fresh water generation system comprises combination of reverse osmosis membranes. Advantages of the hybrid system controlled by the DHM are at least following: Increase efficiency in view of energy consumption, thermal and throughput capacity. Further advantages are at least improved sensitivity to: Water temperature, water salinity and water quality.

[0062] The hybrid system controlled by the DHM improves secure continuous production of high-quality water in the most economical and safe way.

[0063] In an embodiment, the hybrid system comprising evaporator system (EV) and reverse osmosis system (RO) may be arranged in: parallel mode, serial mode or bunkering mode. In parallel mode, the system can operate in EV only mode, RO only mode and EV & RO active mode. In EV & RO active mode the DHM may dynamically adjust share of the fresh water generation between EV and RO, e.g. 60/40, 70/30, 80/20 etc. In serial mode, the system may operate in EV upstream/RO downstream mode or RO upstream/EV downstream mode. In bunkering mode fresh water is bunkered in port, for example.

[0064] In an embodiment, the control algorithm of the DHM is configured to control the hybrid system on different modes and optimize also amount of technical/potable water generations, as well as timing of the generation.

[0065] Hybrid configuration

[0066] Hybrid desalination systems that combine both the thermal and membrane system are studied as an alternative to the conventional standalone systems. A hybrid system can potentially reduce fresh water production cost and improve the plant’s availability and operation flexibility. The MSF method has proven to be a reliable and suitable for large capacity method. However, capex, opex and energy consumption wise it is a rather expensive method. A lot of research has piqued in optimising this process as a standalone system. Where different methods of modelling and simulation has been tested in enhancing the performance of different parts of this system. [0067] Seawater desalting by utilising RO has been proven to be a much more efficient process in terms of energy consumption and capital cost. Moreover, the process has other advantages such as modular structure which makes it flexible to operate for different capacities which in turn, can minimise the system’s down time during maintenance. The process is also conducted at ambient temperature which minimises corrosion hazards. With todays developments the recovery ratios have surpassed of those in MSF. On the other hand, this process would need a pre treatment plant which adds to the complexity of the complete system. Additionally, in the marine sector the sea water properties are subject to constant change and this will cause over sizing and over engineering a sufficient RO plant where it would be sufficient during a vast operating spectrum.

[0068] Due to pros and cons of both the systems mentioned above, hybridization of these systems can bring the best of both systems, and bring the overall process costs down. Combining hybridization between RO and MSF together with power generation plant and waste heat recovery systems can result with even further cost reductions.

[0069] The hybrid system according to different embodiments provide different advantages.

[0070] First, using common, smaller seawater intake systems may result in capital investment savings.

[0071] Second, distillate production from MSF may be blended with the RO permeate in order to obtain concise and right amount of water quality for different purposes.

[0072] Third, a single stage MSF and RO may be used when using a hybrid installation.

[0073] Fourth, RO membrane life may be extended by blending the high quality MSF water production with the RO permeate.

[0074] Fifth, full integration of the RO and MSF plants may provide much better control and efficient sizing of the RO plant. Research has shown that a rather warmer water input to the RO system would cause significant increase in RO water production. Experimental data from studies have revealed the water production increased by 42-48% when the feedwater temperature increases from 15 °C to 33 °C. [0075] Sixth, a shared plant can be utilized in order to blend the productions of RO and MSF for a desired water.

[0076] Seventh, RO system utilizes electrical power while MSF uses heat and electrical power, therefore, this gives more flexibility, for instance during off peak hours more water can be produced and during peak hours RO could be turned off. Additionally, if a heat power is not available or will be costly, electrical power can be used and produce water.

[0077] Eighth, a MSF plant can be used at a reduced load, however, this may cause the efficiency to drop. This fault does not exist in RO since it can easily run on part load. This could also optimize the operation of the water production system.

[0078] A hybrid desalination plant configuration may be determined using a reverse osmosis (RO) model, a multi stage flash (MSF) model and target fresh water flow rate, target fresh water salinity and seawater temperature information.

[0079] Mathematical models may be used to simulate the behaviour of the systems of question in different circumstances.

[0080] Fig. 1 shows a schematic picture of a marine vessel 105 and a marine vessel system 110 according to an example embodiment.

[0081] The marine vessel system 110 comprises a control apparatus 120 configured to determine and operate hybrid desalination plant (HDP) configuration 121.

[0082] When planning a voyage between ports or waypoints, for example, route plan information is determined. The hybrid desalination plant (HDP) configuration 121 is maintained and operated by the control apparatus 120 and receives route plan information for a dedicated route. The route plan information may be generated by the control apparatus 120 or received by the control apparatus 120. The route plan information is generated using information from navigation system 130 that is configured to provide route plan related information based on weather conditions, time schedule, safety aspects and fuel consumption (e.g. based on estimated fuel consumption and weather forecast), for example. As part of the planning steps an estimate of the resources available and possible constraints to the voyage plan are needed as well. Seawater characteristic information associated to the dedicated route may be determined using the route plan information. Furthermore, energy consumption information associated to the dedicated route may be determined using the route plan information. Fresh water consumption information associated with the route plan information may be determined, and dynamic fresh water management model generated using the route plan information, the seawater characteristic information and the water consumption information. Furthermore, a task may be determined relating to fresh water production, fresh water consumption or fresh water bunkering within the marine vessel automatically based on the hybrid desalination plant (HDP) configuration 121.

[0083] Furthermore, characteristic information representing at least one operating characteristic of the marine vessel may be received. The operational characteristics may comprise fresh water generation and/or consumption related information. The hybrid desalination plant (HDP) configuration 121 may be generated using reverse osmosis (RO) model, multi stage flash (MSF) model and target fresh water flow rate, target fresh water salinity and the seawater temperature information.

[0084] In an embodiment, a task may be generated based on the hybrid desalination plant (HDP) configuration 121 , wherein the task may relate to vessel activities (maintenance of sub-systems, heat exchangers, fresh water production, fresh water consumption etc.)By establishing an extended interface between the hybrid desalination plant (HDP) configuration and other systems like the navigation system 130, automation system 190, power generation system 140, propulsion system 150, fresh water generation system (FWGS) 160, energy load system 170 and sensor system 180, for example. It is possible to automate the activities related to planning the energy production and consumption for the voyage and provide an energy voyage plan determining when certain tasks are to be performed and when systems should be ready on standby or switched on/off. The energy voyage plan generated based on hybrid desalination plant (HDP) configuration can include schedules for activating desalination plant configured to pump seawater from sea and desalinate the seawater into freshwater, determine configuration of the plant, schedules for bunkering fresh water at port, changing from evaporation-type desalination plant to reverse osmosis desalination plant or vice versa, schedules for running both plants simultaneously, change of used fuel, change of propulsion (electrical vs. combustion in hybrid ships), activating reliquefaction of LPG system, pumping seawater for used medium in water or gas solutions, such as heat exchangers, change of propulsion energy source (e.g. electric motor powering the propulsion wherein the energy source for the energy motor is changed), or for activating the exhaust gas cleaning system (e.g. SOx or NOx cleaning systems), for example. By establishing a hybrid desalination plant (HDP) configuration for communicating between systems 120-190 it is possible for the on-board systems to negotiate the optimal solution for the voyage. Top priority for optimization may be defined to be safety, and second and third priority can be set by the ship operator (energy efficiency, fuel consumption, speed/time, etc.), for example. The hybrid desalination plant (HDP) configuration operates as a virtual energy pilot for the voyage. The fresh water generation system (FWGS) 160 may be configured to select from at least one of the following fresh water sources: an evaporation-type desalination plant, a reverse osmosis desalination plant, and bunkering, for example. [0085] In an embodiment, the fresh water generation system (FWGS) 160 comprises the desalination plant of the marine vessel 105 that comprises an evaporation-type desalination plant and a reverse osmosis desalination plant. The evaporation-type desalination plant comprises a seawater pumping unit for inputting seawater into the evaporation-type desalination plant; and an evaporator configured to condensate steam generated by evaporating the seawater and to produce the fresh water by collecting the condensed water. The reverse osmosis desalination plant comprises a seawater pumping unit for inputting seawater into the reverse osmosis desalination plant; and a reverse osmosis module configured to produces fresh water by applying pressure to the seawater in a reverse osmosis manner.

[0086] The fresh water generation system (FWGS) 160 may comprise a hybrid desalination plant with a multi stage flash (MSF) subsystem that is a water desalination process where seawater is distilled by flashing portions of the seawater through multiple stages and each stage contains a condenser and areas where fresh water is collected. The stages are connected to each other and a pressure of a first stage is reduced by utilising an ejector pump to decrease ambient pressure and to decrease boiling point of the seawater for allowing flashing to occur. The hybrid desalination plant 160 may comprise common seawater intake systems for the multi stage flash (MSF) subsystem and the reverse osmosis (RO) subsystem.

[0087] Propulsion system 150 may utilize power source to be selected from at least one of the following: combustion-engine based power source; hybrid power source; and full electric power source.

[0088] The hybrid desalination plant (HDP) configuration solution will allow different levels of automation within vessels. In first operation mode, hybrid desalination plant (HDP) configuration may be configured to provide an energy voyage plan, which the engineers can use for scheduling their activities. In second operation mode, hybrid desalination plant (HDP) configuration may be configured to provide an embedded solution, wherein the sub-systems can notify the operator based on the energy voyage plan, when to perform certain tasks or be switched on or set to standby. This notification is repeated on the main display in the engine control room or remote-control station. In third operation mode, hybrid desalination plant (HDP) configuration may be configured to provide a solution to be fully automated and automatically executing the energy voyage plan of the hybrid desalination plant (HDP) configuration 121 with merely notification provided to the operator or remotecontrol station when performing different automated tasks.

[0089] In an embodiment, a server apparatus 107 may be operationally connected over connection 109 to a network 106, such as Internet, and then again over connection 108 to the marine vessel 105. The server apparatus 107 may be configured to determined and maintain the hybrid desalination plant (HDP) configuration 121. The HDP may be downloaded to the marine vessel 105 to control apparatus 120 for operation. At the marine vessel 105 the HDP 121 may be used to control FWGS 160, for example.

[0090] Fig. 2 presents an example block diagram of a control apparatus 120 in which various embodiments of the invention may be applied. The control apparatus 120 is configured to maintain and/or operate the hybrid desalination plant (HDP) configuration 121 .

[0091] The general structure of the control apparatus 120 comprises a user interface 240, a communication interface 250, a processor 210, and a memory 220 coupled to the processor 210. The control apparatus 120 further comprises software 230 stored in the memory 220 and operable to be loaded into and executed in the processor 210. The software 230 may comprise one or more software modules and can be in the form of a computer program product, such as the hybrid desalination plant (HDP) configuration 121 of Fig. 1. The control apparatus 120 may further comprise a user interface controller 260.

[0092] The processor 210 may be, e.g., a central processing unit (CPU), a microprocessor, a digital signal processor (DSP), a graphics processing unit, or the like. Fig. 2 shows one processor 210, but the apparatus 120 may comprise a plurality of processors.

[0093] The memory 220 may be for example a non-volatile or a volatile memory, such as a read-only memory (ROM), a programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), a random-access memory (RAM), a flash memory, a data disk, an optical storage, a magnetic storage, a smart card, or the like. The apparatus 120 may comprise a plurality of memories. The memory 220 may be constructed as a part of the apparatus 120 or it may be inserted into a slot, port, or the like of the apparatus 120 by a user. The memory 220 may serve the sole purpose of storing data, or it may be constructed as a part of an apparatus serving other purposes, such as processing data. A proprietary application 230, such as computer program code for hybrid desalination plant (HDP) configuration, voyage related data, vessel related data, seawater data, sensor data or environmental data may be stored to the memory 220.

[0094] In an embodiment, the apparatus 120 is configured to perform a computer- implemented method for optimizing fresh water generation system of a marine vessel, wherein the fresh water generation system comprises a hybrid desalination plant comprising a multi stage flash (MSF) subsystem and a reverse osmosis (RO) subsystem, and the method comprising: determining a reverse osmosis (RO) model using membrane recovery ratio (RR) and distillate flow rate; determining a multi stage flash (MSF) model using brine salinity, feed salinity and fresh water mass flow rate; receiving target fresh water flow rate, target fresh water salinity and seawater temperature information; and determining hybrid desalination plant configuration using the reverse osmosis (RO) model, the multi stage flash (MSF) model and the target fresh water flow rate, the target fresh water salinity and the seawater temperature information.

[0095] The user interface controller 260 or the user interface 240 may comprise circuitry for receiving input from a user of the control apparatus 120 (an operator), e.g., via a keyboard, graphical user interface shown on the display of the user interfaces 240 of the control apparatus 120, speech recognition circuitry, or an accessory device, such as a headset, and for providing output to the user via, e.g., a graphical user interface or a loudspeaker.

[0096] The communication interface module 250 implements at least part of data transmission. The communication interface module 250 may comprise, e.g., a wireless or a wired interface module. The wireless interface may comprise such as a WLAN, Bluetooth, infrared (IR), radio frequency identification (RF ID), GSM/GPRS, CDMA, WCDMA, LTE (Long Term Evolution) or 5G radio module. The wired interface may comprise such as universal serial bus (USB) or National Marine Electronics Association (NMEA) 0183/2000 standard for example. The communication interface module 250 may be integrated into the control apparatus 120, or into an adapter, card or the like that may be inserted into a suitable slot or port of the control apparatus 120. The communication interface module 250 may support one radio interface technology or a plurality of technologies. The control apparatus 120 may comprise a plurality of communication interface modules 250.

[0097] A skilled person appreciates that in addition to the elements shown in Fig. 2, the control apparatus 120 may comprise other elements, such as microphones, extra displays, as well as additional circuitry such as input/output (I/O) circuitry, memory chips, application-specific integrated circuits (ASIC), processing circuitry for specific purposes such as source coding/decoding circuitry, channel coding/decoding circuitry, ciphering/deciphering circuitry, and the like. Additionally, the control apparatus 120 may comprise a disposable or rechargeable battery (not shown) for powering when external power if external power supply is not available.

[0098] In an embodiment, the control apparatus 120 comprises speech recognition means. Using these means, a pre-defined phrase may be recognized from the speech and translated into control information for the apparatus 120, for example.

[0099] External devices or sub-systems (e.g. elements 130-190 of Fig. 1 ) may be connected to the control apparatus 120 using communication interface 250 of the apparatus 120 or using a direct connection to the internal bus of the apparatus 120.

[00100] Fig. 3 shows a schematic picture of a hybrid desalination plant (HDP) configuration 121 and related information flows according to an example embodiment.

[00101] In an embodiment, computer-implemented method for optimizing fresh water generation system (FWGS) of a marine vessel is provided, wherein the fresh water generation system (FWGS) comprises a hybrid desalination plant comprising a multi stage flash (MSF) subsystem and a reverse osmosis (RO) subsystem, and the method comprising: determining a reverse osmosis model (ROM) using membrane recovery ratio (RR) and distillate flow rate (DFR); determining a multi stage flash model (MSM) using brine salinity (BS), feed salinity (FS) and fresh water mass flow rate (FW); receiving target fresh water flow rate (TFF), target fresh water salinity (TFS) and seawater temperature information (ST); and determining hybrid desalination plant configuration (HDP) using the reverse osmosis model (ROM), the multi stage flash model (MSM) and the target fresh water flow rate (TFF), the target fresh water salinity (TFS) and the seawater temperature information (ST). The fresh water generation system (FWGS) may be controlled using the hybrid desalination plant configuration (HDP).

[00102] In an embodiment, the multi stage flash model (MSM) is configured to use at least one of the following parameters: number of pipes in a condenser, diameter of condenser pipes; heat transfer area in stages, heat exchanger output temperature, and condenser pipe length. These inputs can be received from OPER 330 or from USR 380, for example. [00103] The multi stage flash model (MSM) may be defined using a transient fluid dynamics model.

[00104] Distillate production from the multi stage flash (MSF) subsystem may be controlled to be blended with the reverse osmosis (RO) subsystem permeate in order to obtain desired water quality. The hybrid desalination plant may be configured to use at least one stage of the multi stage flash (MSF) subsystem and a reverse osmosis (RO) subsystem. Hybrid desalination plant configuration (HDP) 121 may be determined by increasing relative use of the reverse osmosis (RO) subsystem when the seawater temperature (ST) increases. Desired water information (TFF and/or TFS) may be received, and in response controlling the hybrid desalination plant to blend water production of the multi stage flash (MSF) subsystem and the reverse osmosis (RO) subsystem based on the desired water information.

[00105] Costs of fresh water productions depends of availability of heat (especially waste heat), electricity and water price in ports. To achieve cost savings for the marine vessel 105 (Fig. 1 ), different methods can be used depending on conditions. Also, water consumption onboard is changing because of ambient air temperature, location of the ship, usage of equipment, which is consuming a lot of water like washing machines. Filling swimming pools requires high amount of water.

[00106] There are some criteria, which should be taken into attention during selection of fresh water source. Performance of reverse osmosis plants is sensitive for sea water temperature (lower temperature means lower capacity), sea water salinity and turbidity. In some areas reverse osmosis plants cannot be used because of poor quality of sea water. Using of fresh water generators in ports should be avoided.

[00107] The ship operators’ decisions which fresh water source should be used in particular situations is currently based on their experience, behaviors or assumptions. This does not guarantee that every time the most optimal way to get fresh water is selected. It means that better planning of water supply during the voyage is needed to increase efficiency and reduce costs. And planning should be done in a predictive manner. The result of optimization of fresh water supply is cost saving and it will have a positive effect on profitable operation of the vessel and/or fleet. Better planning will secure also availability of fresh water. Planning should be based on real-time data, information of the voyage like weather forecast, water temperature and sea water salinity and turbidity on the route, availability of fresh water in ports, and fresh water quality and price in ports, for example.

[00108] Information elements 320-380 may have alternative ways to connect with each other and Fig. 3 only shows one example embodiment. Furthermore, only connections that relate somehow to hybrid desalination plant (HDP) configuration 121 are illustrated. For example, environmental information 340 may also used for route planning and thus for the route plan information 320 but direct connection between blocks 320 and 340 is not shown for simplifying the Fig. 3.

[00109] The hybrid desalination plant (HDP) configuration^ can be configured to operate as a stand-alone solution or as an integrated part of the energy management system/voyage management system/power management system of the marine vessel. The hybrid desalination plant (HDP) configuration 121 enables automation of the fresh water generation process, energy production and consumption, and further enables a higher degree of autonomous operation on board conventional marine vessels and paves the way for energy management for autonomous marine vessels. [00110] In an embodiment, the hybrid desalination plant (HDP) configuration 121 may be interfaced with the navigation system, automation system, power management system and sub-systems like water solutions, engines and generators, as shown in Fig. 1 , for example. The hybrid desalination plant (HDP) configuration^ may further be configured to receive and manage information about the health status of sub-systems directly or through the power management and automation systems. The hybrid desalination plant (HDP) configuration 121 can generate tasks and/or instructions for the automation and power management systems based on route plan information, seawater characteristic information and operational characteristics of the marine vessel, such as fresh water consumption information.

[00111] The hybrid desalination plant (HDP) configuration 121 may be arranged to receive route plan information 320 including information like weather forecasts, navigation information for the dedicated route, waypoint information for the dedicated route, emission restricted areas, environmental restrictions and other relevant information. The route plan information 320 may be received from the navigation system of the marine vessel system or the route plan information 320 may be generated by the control apparatus 120. The route plan information 320 may comprise at least one of the following: navigation information for a waypoint or a port; target time or arrival information for the waypoint or the port; fresh water bunkering information for the port; and environmental information associated to at least one route of the route plan information. The navigation information may comprise at least one of the following: destination information of the dedicated route; remaining travel time of the dedicated route; remaining distance of the dedicated route; navigation information for the dedicated route; waypoint information for the dedicated route; emission restricted area information of the dedicated route; and environmental restriction information of the dedicated route.

[00112] Route plan information 320 or environmental information 340 may comprise seawater characteristic information that comprises at least one of the following: seawater temperature information; seawater salinity information; and seawater quality information. Route plan information 320 may comprise predicted seawater characteristic information and environmental information 340 may comprise actual seawater characteristic information in real-time at the vessel, for example.

[00113] The hybrid desalination plant (HDP) configuration) 121 is further arranged to receive operational characteristic information 330 representing at least one operating characteristic of the marine vessel. The operating characteristic information (OPER) 330 of the marine vessel may comprise at least one of the following: membrane recovery ratio (RR), distillate flow rate (DFR), brine salinity (BS), feed salinity (FS), and fresh water mass flow rate (FW). The operating characteristic information (OPER) 330 may also comprise information about used fresh water generation plant (evaporation or reverse-osmosis), status of the fresh water storage tank, amount of waste heat or energy available to be used for the evaporator, parameters of the fresh water generation plants, operation mode of the fresh water system; operation status of the fresh water system; information on currently active plant; status information of energy generation sub-system; and status information of energy storage sub-system, such as a battery system. [00114] The operational characteristics 330 may also comprise fresh water consumption information associated with the route plan information 320.

[00115] Energy consumption information 360 associated to the dedicated route may be determined using the route plan information 320. The energy consumption information 360 relates to predicted energy consumption of at least one of the following: fresh water generation of the marine vessel, hotel load of the marine vessel, at least one propulsion device of the marine vessel, and automation system of the marine vessel. The hotel load may represent load relating to at least one of lighting, heating, and ventilation during the dedicated voyage. Thus, hotel load may relate to any electrical load caused by all systems on a vehicle (especially a marine vessel) other than propulsion. Energy consumption information 360 may comprise planned energy consumption in relation to different tasks and health status information and availability of the vessel systems during the voyage and used as an input for the hybrid desalination plant (HDP) configuration) 121.

[00116] In case there are constraints in the access to power or a mismatch between production and consumption of energy (consumption exceeds the possible production), the hybrid desalination plant (HDP) configuration^ may generate dynamic change proposals to the route plan information 320 or schedules for desalination plants (EV or RO) or bunkering, for example. The energy consumption information 360 is received by the hybrid desalination plant (HDP) configuration^ . [00117] In an embodiment, the hybrid desalination plant (HDP) configuration 121 may be configured to automate interaction between navigational route planning and energy route planning. Such operation may include scheduling of energy consumption (use of equipment) and energy generation, especially related to fresh water generation along the route.

[00118] In an embodiment, the control apparatus 120 may be configured to determine a task relating to the route plan information 320 automatically based on the hybrid desalination plant (HDP) configuration^ . Thus, the route plan information 320 that is determined for a dedicated route, may be dynamically adjusted automatically using the hybrid desalination plant (HDP) configuration 121. [00119] In an embodiment, the control apparatus 120 may be configured to dynamically adjust navigation information of the route plan information. Furthermore, the control apparatus 120 may be configured to dynamically adjust navigation information for the dedicated route, and, for example, dynamically adjusting waypoint information for the dedicated route.

[00120] In an embodiment, the control apparatus 120 may be configured to dynamically adjust destination information or remaining travel time of the dedicated route.

[00121] The energy consumption information 360 may be configured to be defined using also other input information than only the route plan information 320. For example, characteristics information 330, environmental information 340 or operator input 380 may be used together with the route plan information 320.

[00122] The hybrid desalination plant (HDP) configuration 121 may further be arranged to receive environmental information 340 separate or in addition to possible environmental information included in the route plan information 320. The environmental information 340 may represent at least one current environmental characteristic of the marine vessel, such as seawater characteristic information, seawater salinity (SS), and seawater quality (SQ); weather information; weather forecast information; wind information; air pressure information; ice information; wave height, frequency or direction information; tidal data; current information; and roll or pitch information. The seawater characteristic information may comprise at least one of the following: seawater temperature information (ST); seawater salinity information (SS); and seawater quality information (SQ).

[00123] In an embodiment, the control apparatus 120 may be configured to schedule gas solutions related operations, such as reliquefaction process using seawater as coolant in heat exchangers, energy consumption operations or energy generation operations using a determined task relating the route plan information automatically based on the hybrid desalination plant (HDP) configuration 121. The scheduling may be based on the hybrid desalination plant (HDP) configuration 121 generated using at least one of the following: available waster heat/energy within the marine vessel, predicted fresh water consumption, seawater temperature information, emission restricted area information of the dedicated route; and environmental restriction information of the dedicated route.

[00124] In an embodiment, if there has not been identified any violations of possible constraints, the hybrid desalination plant (HDP) configuration 121 may generate at least one task for controlling an automation element of the automation system 350 within the marine vessel automatically based on the hybrid desalination plant (HDP) configuration 121 and control the associated automation element of the marine vessel automation system 350 based on the determined task. Controlled system may comprise, for example, the fresh water generation system (FWGS).

[00125] In an embodiment, the automation element of the marine vessel automation system 350 is configured to control at least one of the following: fresh water generation system (FWGS) that comprises a desalination plant configured to pump seawater from sea and desalinate the seawater into freshwater, route planning system for next waypoint or port, voyage management system for optimizing the optimal speed profile, and water bunkering at port.

[00126] For example, the route planning system may carry out following procedures: A) Calculate and balance to what degree a route deviation to warmer and/or cleaner water will benefit the overall economy. B) Generate an operational plan for when to run evaporator-plant and when reverse-osmosis plant and when to bunker during the planned route. C) If the preferred port arrival time is known, calculate the optimal speed profile including staying longer in warmer/cleaner waters and avoiding waiting time in cold waters. Additionally, the system may collect real operating data, compare it with the original hybrid desalination plant (HDP) configuration based prediction/recommendation, and automatically improve the recommendation for later voyages operated by hybrid desalination plant (HDP) configuration 121 .

[00127] In an embodiment, the automation 350 of the marine vessel automation system 350 may further be configured to control at least one of the following: power management system of the marine vessel and navigation system of the marine vessel. The automation element may be configured to control, for example, power management system of the marine vessel for at least one of the following: schedule for changing propulsion power source; schedule for changing used fuel; schedule for activating exhaust gas cleaning system (e.g. SOx or NOx cleaning systems); and schedule for operating HVAC (Heating, Ventilation and Air Conditioning). The automation element may also be configured to control, for example, power management system of the marine vessel for schedule for changing operating modes of combustion engine(s) or other power sources (in so far, these operating modes influence efficiency of the power generation, for example).

[00128] In an embodiment, the automation element 350 of the marine vessel is configured to control at least one of the following: a pump for the seawater; a filter for the seawater pumped from the sea; an evaporator for an evaporation-type desalination plant; a pre-filter or reverse osmosis element for a reverse osmosis desalination plant; a collecting tank for fresh water; a post-treatment element for potable water; a heat exchanger sub-system; a power management system; and a navigation system.

[00129] In an embodiment, operational characteristics 330 of the desalination plant may be determined, wherein the operational characteristics comprises at least one of the following: information about used type of desalination; operation mode of the desalination plant; and fresh water storage status of the desalination plant. The fresh water consumption information may be determined using the environmental information. Energy consumption information may be determined based on the HDP 121 , wherein the energy consumption information represents predicted energy consumption for fresh water generation system and of at least one of the following: hotel load of the marine vessel, swimming pool load of the marine vessel, washing machine load of the marine vessel, potable water generation load, and automation system load of the marine vessel.

[00130] In an embodiment, if there has not been identified any violations of possible constraints, the HDP 121 may generate energy voyage plan (EVP) 370 and utilize the energy voyage plan (EVP) 370 for determining control tasks relating to fresh water generation systems, fresh water consumption systems, energy production, energy consumption or energy storage within the marine vessel automatically based on the HDP 121. [00131] While cruising and performing transit during the voyage, the HDP 121 maintains a dynamic and up-to-date situational awareness in relation to the executed route (navigation) and energy route plan and the continued health status from all energy consumers and producers. If the situation changes and a system changes health status, the HDP 121 may be configured to update the energy voyage plan 370 including tasks and automatically notifying the navigation system to allow the navigation system to modify the route plan information accordingly.

[00132] Because the HDP 121 has access to information about optimal operation conditions of the sub-systems, the model can help to avoid stressing engines, generators and other subsystems, as the safety limit parameters are known to the HDP 121. An operating mode may be used wherein only confirmed request from the operator is needed, and the HDP 121 may allow running sub-systems outside the optimal operation conditions.

[00133] The energy voyage plan 370 information can be provided in a first mode as a schedule made available to the engineers to follow. The engineers may perform the scheduled tasks for the automation system 350 based on the energy voyage plan 370. In a second mode, the energy voyage plan 370 may be embedded in the main display of the engine control room and the power management system, for example. The automation system may be further configured to provide an integrated guidance tool to prompt the operator when a task should take place and by acknowledgement from the operator enable and perform the task and end the task when performed. A third mode allows a fully automated solution, where the operator may only be informed about the energy voyage plan 370 or the tasks determined by the HDP 121. Optionally, current status of the HDP 121 and next steps may be informed to the operator but the HDP 121 is configured to control automation elements automatically. In such embodiment the energy voyage plan 370 may be optional.

[00134] It is possible to override the HDP 121 by changing it to standby mode and allowing a manual operation of the fresh water generation systems, power management and automation systems and the sub-systems. At the third mode, the HDP 121 can operate autonomously together with the navigation system and all the sub-systems. Instead of notifying the operator, the HDP 121 may log (e.g. using the energy voyage plan 370) the activities and events and will only request assistance from the mission controller or a human operator in case the HDP 121 is facing a situation it cannot handle or it is not available for operation.

[00135] In an embodiment, the energy voyage plan 370 may also comprise automatic information being sent to port authority system for approaching arrival. The information being sent may relate to, for example, estimate of fuel, fresh water, power and/or energy required while staying at berth. By doing that the harbor authorities can make a better estimate how much LPG/LNG, fresh water and electricity they need to buy on the spot market for the vessel about to be docked. The port information system may have a HDP of its own that receives inputs from all vessels arriving to the port.

[00136] The HDP 121 may be configured to control sub-systems and fuel operations via the automation and power management systems and the HDP 121 can e.g. automatically negotiate the planned route with the navigation system based on the availability of energy producers and their health status (able to operate 0- 100%), fresh water generation sub-systems, seawater characteristics, and the planned energy/fresh water consumption in relation to ship operation, time and ship position, for example.

[00137] In an embodiment, the HDP 121 is configured to receive input from an operator (USR) 380 either on-board the vessel or remote at other vessel or ground station, for example. In certain pre-defined operating modes or tasks, it may be required that operator acknowledgement is received from the operator (USR) 380 for the determined task the HDP 121 before controlling an automation element of the marine vessel based on the determined task in response to the received operator acknowledgement.

[00138] In an embodiment, the HDP 121 may be updated in real-time using the route plan information 320, the environmental information 340 and the operational characteristics 330, such as fresh water consumption information. In an embodiment, when receiving confirmation from the operator 380 of the task being performed, the HDP 121 is updated in response to the received confirmation. [00139] In an embodiment, in autonomous vessel operation mode, automatic route planning may be executed to provide the route plan information 320 for a safe and optimized route taking into account planned destination and ETA, up to date chart data from the ECDIS, draft of the vessel, predicted environmental conditions (ocean current, wind and sea state) as well as status information's from the power and propulsion plant. Furthermore, a contingency plan to stop the vessel safely in case of emergency is generated along the route for every leg or even leg segment, for example. The approval mechanisms of the route plan 320 may vary depending on autonomy level in use, authority rule sets and customer specifications. Once the route plan is activated and being executed by the Integrated Navigation / DP System (Trackpilot, Speedpilot, DP), the control system is permanently monitoring and adapting the route execution with regards to track- and schedule keeping) if necessary. Reasons for adaptation can be, for example: new destination and/or new ETA, differences between predicted and real environmental conditions, collision avoidance maneuvers, and unexpected changes in the propulsion / power plant (i.e. unforeseen equipment failure).

[00140] In an embodiment, efficiency fresh water generation using seawater as source medium is greatly improved if planning the used route between ports or waypoints. That would result with overall energy savings no matter the travelled route might slightly increase. When knowing weather forecasts, sea temperatures at different areas as well as some vessel operational parameters relating to fresh water generation solutions of the vessel, a computer implemented SW algorithm or model is provided that optimizes both the used route as well as optimal times/places to carry out pumping and generating fresh water out of seawater, for example. The route information or target information may also comprise some port information, like time slot for allocated berth. Thus, the available time to spend to wait for available berth could be optimized so that either route for the port or stand-by position for waiting the open slot could be optimized based on sea water characteristics and vessel operational characteristics, such as fresh water consumption information. Not only seawater temperature may be used, but also other parameters like salinity level, water quality etc. can be used if affecting the efficiency of fresh water generation process.

[00141] In an embodiment, the HDP 121 is configured to determine an operational plan comprising tasks to control at least one of the following: time and location to run desalination plant related processes along a route of the route plan information; and time and location to bunker fresh water at a port along a route of the route plan information.

[00142] In an embodiment, waste heat from a waste heat energy utilization system fitted on the marine vessel, is operationally connected to an evaporation-type desalination plant to be used for boiling water of an evaporator, and the method further comprises determining status of the waste energy utilization system; and determining the task configured to control fresh water production in the evaporationtype desalination mode based on the status. The waste heat energy utilization system comprises at least one of the following: a boiler installed in an exhaust passage of an engine wherein exhaust heat energy is utilized to generate steam from water; excess steam from vessel boilers and economisers; and jacket cooling water of an engine.

[00143] The HDP 121 may be configured to receive actual operating data; compare the actual operating data with predicted data generated by the HDP 121 to provide error data; and adjust the HDP 121 based on the error data.

[00144] Reverse Osmosis (RO) modelling

[00145] In a Reverse Osmosis (RO) process a partially permeable membrane is used to remove ions, unwanted species and other particles in order to form drinkable water. Osmosis is the movement of solvent from a less dense region to a denser region. This movement in which equalises the concentration between the two sides of a membrane generates a pressure which is called the osmotic pressure. In reverse osmosis an applied pressure overcomes the osmotic pressure and pushes the higher solute fluid through a set of membranes in order to purify it.

[00146] The process is very similar to membrane filtration, however, the predominant removal mechanism in membrane filtration is straining, or size exclusion, whereas, in reverse osmosis the purifying involves a diffusive mechanism so that other parameters such as, pressure, water flux and solute concentration are also affecting the water throughput. The mathematical model proposed in this study is as follows:

[00147] The feed flow rate Mf based on the membrane recovery ratio (RR) and the distillate flow rate (Md) is:

[00148] The distillate’s salt concentration Xd is:

[00149] Where, Xf is the feed flow rate salt concentration and SR is the salt rejection percentage.

[00150] The rejected brine is determined from mass balance as follows:

[00151] The rejected salt concentration (kg/m3) is calculated by:

[00152] The temperature correction factor (TCF) is found by the relation below:

[00153] Where “t” is the seawater temperature.

[00154] There are two permeability coefficients that need to be calculated. One is the water permeability and the other is the salt permeability. They are represented as kw and ks respectively:

[00155] Where FF is the membrane fouling factor. The next section will illustrate how to calculate osmotic pressure for the feed, brine and distillate sides. 75.84

[00156] The average osmotic pressure on the feed side is represented as: [00157] Therefore, the net osmotic pressure across the membrane is represented

[00158] The net pressure difference across the membrane is represented as:

[00159] Where:

Ae Membrane area (m2) nv Number of the pressure vessels ne Number of the membrane elements

[00160] With the calculations above, the needed pump power (kW) is calculated as the following:

[00161] Where p_f is the feed flow rate’s density, and q_p is the pump’s mechanical efficiency. With the power calculation above the specific power consumption (kWh/m3) is calculated as:

[00162] Usually a recovery turbine is used to recover some of the brine’s energy. The outlet pressure is set as 101.15 kPa. Consequently, the power recovered is calculated as follows:

[00163] The total power required, is, therefore:

[00164] Multistage Flash (MSF) modelling

[00165] Multistage flash distillation is a water desalination process where the sea water is distilled by the means of flashing portions of the water through multiple stages. Each stage contains a condenser and areas where the fresh water is collected. The stages are connected to each other and the first stage’s pressure is reduced by utilising an ejector pump. Decreasing the ambient pressure will decrease the boiling point of sea water, allowing flashing to occur. [00166] Ideally, for an optimisation study and a process like MSF one would need a transient model. From the previous report regarding modelling the MSF process, a model is created which is predicting the process’s behaviour in a transient manner. The methodology for this study is based on a one-dimensional computational fluid dynamics model. Ideally, this model could be used for this optimisation, however, due to some limitations an analytical model was developed also for the MSF process.

[00167] Feed stream’s mass flow rate (kg/s) to the mixer unit is obtained via:

[00168] Where Sb is the brine salinity, Sf is the feed’s salinity and Md is the distillate’s (Fresh water’s) mass flow rate (kg/s).

[00169] Total needed feed (Mft) is based on the first splitter ratio:

[00170] Therefore, the rest of feed loss:

[00171 ] And the brine mass flow rate:

[00172] The stage temperatures are defined based on top brine temperature (TBT), last stage’s temperature and the number of the stages (N):

[00173] The recycle brine mass flow rate is calculated as follows:

[00174] Where Y is the extraction percentage and N is the number of stages. Physically, Y us the specific ration of the sensible heat and latent heat and is equal to:

[00175] As a result the salinity of the recycle stream can be calculated as:

[00176] Outlet temperature of the distillate product Td is known based on the last stage brine temperature Tn, non-equilibrium allowance (NEA) and boiling point elevation (BPE).

[00177] Based on experimental studies, a quadratic relation has been extracted based on regressions in order to represent NEA and BPE in a window of operating conditions.

[00178] These equations are valid while the sea water temperature is between 0 and 200 °C and the seawater salinity is between 0 and 0.12 kg/kg. The accuracy of these models is determined to be as ±0.0018K.

[00179] Cost modelling

[00180] In order to be able to optimize the proposed system, determination of operating and capital costs of the systems in comparison to hybrid systems is needed.

[00181 ] MSF Cost modelling

[00182] The depreciation period of 15 years and 5% interest rate is used. The formula to predict the direct capital cost for an MSF plant is as follows:

[00183] Where <t> is a fixed capital coefficient for MSF, AT is the total heat transfer area and Wd is distillate product flow-rate, kg/h. <t> could take a value between 5000 and 9000.

[00184] Indirect capital investment:

[00185] The operation costs are modelled as follows:

[00186] Steam cost:

[00187] Where (W_S ) ^— is the total steam consumption including ejector motive steam, kg/h. TS is representing Steam temperature to brine heater (°C).

[00188] Chemical treatment

[00189] Where m ’ feed is the feed flow rate (kg/h) and p_B is the density of brine.

[00190] Power cost ( )

[00191 ] Where m ’_d is distillate flow rate (kg/h) and p_w is the pure water density.

[00192] Spares cost

[00193] Labor cost

[00194] Operating costs are subsequently calculated as:

[00195] The total cost would then be calculated as (can be done separately for first and second cost information):

[00196] First cost information may be determined for the reverse osmosis (RO) subsystem based on the reverse osmosis (RO) model.

[00197] Second cost information may be determined for the multi stage flash

(MSF) subsystem based on the multi stage flash (MSF) subsystem model.

[00198] Hybrid desalination plant configuration (HDP) 121 may be determined using the first and second cost information.

[00199] The first and second cost information may comprise capital cost information and operational cost information.

[00200] CDM relates to direct capital cost, CIM relates to indirect capital investment and COM relates to operating costs.

[00201 ] RO Cost modelling

[00202] The direct and indirect capital costs are estimated, additionally, operating costs are approximated subsequently.

[00203] The initial capital cost which is modelled is the membrane cost, where it is calculated as follows: [00204] Where Cmem is the module cost and Amod is the module membrane area. In addition, Am is the membrane area needed by the RO plant.

[00205] Discovering models and experimental data may be determined regarding plants of a size of a marine application which is a fraction of the more researched land-based plants.

[00206] Civil work

[00207] Pumping and energy recovery system

[00208] Where m ’_fw is the total fresh production and P is the pressure where the RO plant is operating at. Rf is representing the RO plant’s recovery fraction.

[00209] Intake and pre-treatment costs:

[00210] Direct capital cost

[00211 ] If the capacity ratio is:

[00212] , then the annual RO direct capital cost becomes: [00213] Indirect capital cost

[00214] Operation and maintenance costs includes:

[00215] Membrane replacement (Assuming a 20% membrane replacement per year)

[00216] Chemical treatment costs

[00217] Spares costs

[00218] Labour costs

[00219] The total power needed was discussed in the previous section were HPneeded was illustrated. The same formula is used in this section to calculate the cost of operating the recovery turbine (the efficiency of this turbine is assumed as 0.8):

[00220] Where “time” is the duration which the plant is operated and EPP is the pre post treatment cost energy needed for the turbine energy recovery. This cost is calculated as:

[00221] Wy is representing yearly total plant capacity (m3/y).

[00222] To sum up, the total operation cost is:

[00223] Therefore, the annual cost is as follow:

[00224] Typically, optimization problem needs objectives and parameters where the systems can change in order to satisfy the asked objectives. Embodiments focus on, for example, an objective where cost of water production is minimized. Following sample cases and results of modelling and optimization are disclosed.

[00225] Case 1 :

[00226] In this case two plants are working independently and only sharing the inlet. The throughput is shared between the two systems. About one third of the clean water is produced by MSF and the other two third of the demanded fresh water is produced by RO. Tablei illustrates the properties of each systems for all the hybrid cases.

[00227] Case 2 & 3: [00228] In these two hybrid cases, a single stage RO unit is coupled with an MSF unit. In case 2 the intake for the RO unit is from the warm MSF blowdown, while in case 3 the feed to the RO unit is shared with the feed for the MSF unit (at sea temperature). In case 2 the Fresh water produced from RO and MSF are mixed as well as the brine reject. In case 3 though, part of the seawater is blended with the RO unit reject and form the MSF inlet stream.

[00229] Case 4:

[00230] Case 4 and case 2 are similar in the fact that the RO feed’s properties are kept constant by utilizing the MSF plant. The difference, however, lays in how the MSF system is laid out. In this this idea the MSF plant is divided in two sections where one section is the heat recovery section and the other part is heat rejection section. The heat rejection section is larger than the heat recovery section. In the heat rejection section seawater is fed through, where it rejects thermal energy from the plant and discharge the product and brine at the lowest possible temperature. The water is heated by different means (Boiler, heat exchanger with waste heat recovery, etc.) to the saturation pressure of the maximum available pressure. The advantage of this case is that where the inlet feed to the RO unit will have a constant and high temperature similar to cases 2 & 3. This will in turn cause less capital and maintenance cost as well as better RO performance. On the other hand, the MSF system would need to be modified in order to still be able to produce the demanded water. Experimental data reveal an approximately 40% increase in freshwater production by pre heating the RO plant section up to 33 °C. This is compared to when the inlet feed is set as 15 °C. Additionally, a common seawater intake for both plants will result in saving in capital cost. Furthermore, a common post treatment system which treats the blended freshwater product from both systems will also cause a reduction in capital costs.

Table 1 : Case properties

[00231 ] Reference case that is studied is 1000 m3/day with a salinity of 4% and the seawater temperature of 15 °C. In Table “1 ” the power needed for operating a standalone system as well as other proposed cases are exhibited. [00232] As can be seen, two stage RO plant proves to be the most cost efficient in terms of water production especially for new built systems.

[00233] Using different models and their optimization, it is showed that hybridization of the RO and MSF processes would result in better economics and better performance. In terms of water production with these examples we could not achieve water production costs lower than the standalone double stage RO systems.

However, looking at capital costs the models show promise in comparison with the standalone RO system. The hybrid systems show lower costs in every department when comparing with MSF standalone system (water production costs are lowered for an average of 20%). Traditionally, an MSF system is known as a more reliable system, where in some of the ideas although, the systems are integrated, the MSF system can run independently, in case of an unexpected shutdown of the RO plant. Furthermore, sharing facilities (i.e. common intake and outfall facilities) is worth consideration for any possible retrofit cases.

[00234] In an embodiment, the control apparatus 120 may be configured to determine first cost information for the reverse osmosis (RO) subsystem based on the reverse osmosis (RO) model (ROM), determine second cost information for the multi stage flash (MSF) subsystem based on the multi stage flash (MSF) subsystem model (MSM); and determine hybrid desalination plant configuration (HDP) 121 using the first and second cost information. The first and second cost information may comprise capital cost information and operational cost information.

[00235] Fig. 4 presents an example block diagram of a server apparatus 107 in which various embodiments of the invention may be applied.

[00236] The general structure of the server apparatus 107 comprises a processor 410, and a memory 420 coupled to the processor 410. The server apparatus 107 further comprises software 430 stored in the memory 420 and operable to be loaded into and executed in the processor 410. The software 430 may comprise one or more software modules and can be in the form of a computer program product.

[00237] The processor 410 may be, e.g., a central processing unit (CPU), a microprocessor, a digital signal processor (DSP), a graphics processing unit, or the like. Fig. 4 shows one processor 410, but the server apparatus 107 may comprise a plurality of processors.

[00238] The memory 420 may be for example a non-volatile or a volatile memory, such as a read-only memory (ROM), a programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), a random-access memory (RAM), a flash memory, a data disk, an optical storage, a magnetic storage, a smart card, or the like. The server apparatus 107 may comprise a plurality of memories. The memory 420 may be constructed as a part of the server apparatus 107 or it may be inserted into a slot, port, or the like of the server apparatus 107 by a user. The memory 420 may serve the sole purpose of storing data, or it may be constructed as a part of an apparatus serving other purposes, such as processing data.

[00239] The communication interface module 450 implements at least part of radio transmission. The communication interface module 450 may comprise, e.g., a wireless or a wired interface module. The wireless interface may comprise such as a WLAN, Bluetooth, infrared (IR), radio frequency identification (RF ID), GSM/GPRS, CDMA, WCDMA, LTE (Long Term Evolution) or 5G radio module. The wired interface may comprise such as universal serial bus (USB) or National Marine Electronics Association (NMEA) 0183/2000 standard for example. The communication interface module 450 may be integrated into the server apparatus 107, or into an adapter, card or the like that may be inserted into a suitable slot or port of the server apparatus 107. The communication interface module 450 may support one radio interface technology or a plurality of technologies. Captured or generated hybrid desalination plant configuration related data, model data, voyage data, seawater characteristics data, fresh water consumption information, vessel characteristics data or environmental data, for example, may be received by the server apparatus 107 using the communication interface 450. Data may be stored for backup or processed and provided to a control apparatus 120. The data may be utilized for hybrid desalination plant configuration of another marine vessel, for example.

[00240] The e-mail server process 460, which receives e-mail messages sent from control apparatuses 120 and computer apparatuses via the network. The server 460 may comprise a content analyzer module 461 , which checks if the content of the received message meets the criteria that are set for new activity data item of the service. The content analyzer module 461 may for example check whether the e-mail message contains a valid vessel activity data item to be used for hybrid desalination plant configuration processing, for example. The valid data item received by the e- mail server is then sent to an application server 440, which provides application services e.g. relating to the user accounts stored in a user database 470 and content of the content management service. Content provided by the service system is stored in a content database 280.

[00241] A skilled person appreciates that in addition to the elements shown in Fig. 4, the server apparatus 107 may comprise other elements, such as microphones, displays, as well as additional circuitry such as input/output (I/O) circuitry, memory chips, application-specific integrated circuits (ASIC), processing circuitry for specific purposes such as source coding/decoding circuitry, channel coding/decoding circuitry, ciphering/deciphering circuitry, and the like.

[00242] Fig. 5 shows a flow diagram showing operations in accordance with an example embodiment of the invention.

[00243] In step 500, a computer-implemented method for optimizing fresh water generation system of a marine vessel, wherein the fresh water generation system comprises a hybrid desalination plant comprising a multi stage flash (MSF) subsystem and a reverse osmosis (RO) subsystem, is started. In step 510, a reverse osmosis (RO) model is determined using membrane recovery ratio (RR) and distillate flow rate. In step 520, a multi stage flash (MSF) model is determined using brine salinity, feed salinity and fresh water mass flow rate. In step 530, target fresh water flow rate, target fresh water salinity and seawater temperature information are received. In step 540, hybrid desalination plant configuration is determined using the reverse osmosis (RO) model, the multi stage flash (MSF) model and the target fresh water flow rate, the target fresh water salinity and the seawater temperature information. The method is ended in step 550.

[00244] Fig. 6 shows a fresh water generation system 600 in accordance with an example embodiment of the invention. The fresh water generation system 600 may be controlled using the hybrid desalination plant configuration 121.

[00245] Sea water inlet 605 is used for pumping sea water in. A filter may be arranged downstream the inlet. Seawater characteristics may be determined. Evaporator 610 is shown that may utilize heat from the heat exchanger 615 or waste heat from the vessel system. Technical water may be available directly or as stored in storage collecting tank 620. Post-treatment may be carried out for generating potable water to be distributed. Pre-filter 625 and reverse osmosis 630-631 are shown in second fresh water generation path of Fig. 6. Rejected brine is stored to brine collection tank 635

[00246] As shown, the system 600 may comprise Evaporator and Reverse Osmosis Plant integrated in one unit with common control apparatus 120. Integrated Automation System (see e.g. Fig. 3) may collect real-time data and forecast data (weather, sea water temperature and quality, availability and prices of fresh water in ports, where a ship will stop). The system with various data sources and continuous monitoring enables fact based decisions with visual user-friendly interfaces and/or provides fully autonomous operation. Such hybrid system will secure continuous production of high quality water in the most economical and safe way.

[00247] In an embodiment, the evaporator 610 and the reverse osmosis 630-631 plant will be combined in one hybrid unit having common control model 121. This common control model 121 is connected to the ship Integrated Automation System. It may utilize location data (GPS), sea water temperature, and air temperature including weather forecast, for example. Such common control system may be used to generate a digital twin. The control system should have data of water temperature and quality linked to the location. This information can be uploaded or available from a cloud service. Availability of fresh water and its price should be entered to the control of the hybrid system model 121 in advance according to the ship route. In cases when ships should give reports related to fresh water production and brine discharge to port authorities. These reports can be generated automatically using the control apparatus 120 and configuration model 121 .

[00248] The model 121 can be connected to the customer’s office and support office through the cloud service for remote monitoring and control. Remote control and monitoring are optional features available upon the customer’s request.

[00249] Based on real-time and forecasted data the control apparatus 120 is able to calculate the most optimal scenario for fresh water production using the digital twin of the physical asset. The digital twin is based on the mathematical model. The quality of insight provided by the digital twin is continuously monitored and any necessary corrective actions taken. Monitoring may reveal that a new version of the digital twin needs to be generated. As further insights and data are collected, it will be possible to utilize technology such as machine learning to assist and improve the optimization.

[00250] In an embodiment, when using digital twin, the control apparatus 120 allows to simulate and analyze what has happened in the past, optimize what is happening now, and predict what will happen in the near future - with far greater accuracy and reliability than previously possible. Control apparatus 120 and the configuration model 121 can save costs, energy, man-hours and provides fully autonomous operation. In case of malfunction of the common control system there should be an opportunity to run the evaporator and/or the reverse osmosis plant in manual mode to guarantee availability of fresh water onboard.

[00251] In an embodiment, the reverse osmosis (RO) subsystem 630-631 is configured to utilize electrical power and the multi stage flash (MSF) subsystem 610 is configured to utilize heat and electrical power. The reverse osmosis (RO) subsystem 630-631 may be controlled to be operated at a reduced load by the hybrid desalination plant configuration 121.

[00252] In an embodiment, the hybrid desalination plant 600 comprises reverse osmosis (RO) subsystem 630-631 and the multi stage flash (MSF) subsystem 610 to operate independently but sharing a common inlet 605.

[00253] HDP 121 may control throughput to be shared between the reverse osmosis (RO) subsystem and the multi stage flash (MSF) subsystem so that 25-40% of the fresh water is produced by the multi stage flash (MSF) subsystem and 60-75% of the fresh water is produced by the reverse osmosis (RO) subsystem.

[00254] One option is that 30-35% of the fresh water is produced by the multi stage flash (MSF) subsystem and 65-70% of the fresh water is produced by the reverse osmosis (RO) subsystem.

[00255] Fig. 7 shows a fresh water generation system 700 in accordance with an example embodiment of the invention.

[00256] Fig. 7 illustrates operational elements and their interconnections. Vessel integrated automation system (IAS) 745 may be connected to network 106. Also the control apparatus 120 of the hybrid fresh water generation system 725 may be directly connected to the network 106 but for simplicity in Fig. 7 the network connection for control apparatus 120 is drawn through IAS 745. The hybrid system 725 comprises a RO plant 710 and EV plant 715 that may use common intake of seawater 605. Technical water 730 is provided by the hybrid system 725, as well as potable water 740 through post-treatment 735.

[00257] Various embodiments have been presented. It should be appreciated that in this document, words comprise, include and contain are each used as open-ended expressions with no intended exclusivity. If desired, the different functions discussed herein may be performed in a different order and/or concurrently with each other. Furthermore, if desired, one or more of the above-described functions may be optional or may be combined. Although various aspects of the invention are set out in the independent claims, other aspects of the invention comprise other combinations of features from the described embodiments and/or the dependent claims with the features of the independent claims, and not solely the combinations explicitly set out in the claims.

[00258] Without in any way limiting the scope, interpretation, or application of the claims appearing below, a technical effect of one or more of the example embodiments disclosed herein is improved method and apparatus for automated marine vessel energy management and fresh water generation. Another technical effect of one or more of the example embodiments disclosed herein is improved method and apparatus for autonomous marine vessel control.

[00259] Another technical effect of one or more of the example embodiments disclosed herein is that it enables performing the marine vessel energy production/consumption or energy storage related tasks automatically in the safest and most efficient way possible. Optionally, while the operator may have oversight, the control model based automation may be principally handled by software in autonomous mode.

[00260] Another technical effect of one or more of the example embodiments disclosed herein is that safety is improved since there is less likelihood of human error, less wear and tear since the energy management related devices and systems are efficiently utilized, and greater efficiency that allows reduced operating costs.

[00261] Although various aspects of the invention are set out in the independent claims, other aspects of the invention comprise other combinations of features from the described embodiments and/or the dependent claims with the features of the independent claims, and not solely the combinations explicitly set out in the claims.

[00262] It is also noted herein that while the foregoing describes example embodiments of the invention, these descriptions should not be viewed in a limiting sense. Rather, there are several variations and modifications, which may be made without departing from the scope of the present invention as defined in the appended claims.